This research is directed at the clarification of the process of myelinogenesis by examining the proteins and the mode of assembly and maintenance of myelin in the murine mutants Jimpy, Quaking and MSD. Recent findings in our laboratory indicate that the Quaking mutant represents a model system of a disordered process of membrane assembly. It is planned to systematically examine the synthesis, maintenance and turnover of myeline proteins and lipids in this mutant using a double label method which significantly improves the capability of examining incorporation into proteins and lipids of brain and of its subcellular membrane fractions. This approach to the molecular mechanisms of myelinogenesis will progress to work upon the isolation, characterization and study of incorporation of radiolabelled precursors to: (a) proteolipid protein of brain and myelin; (b) mylein subfractions; (c) preparation of purified axons, and (d) myelin of the PNS.